Using cotton-candy machines to produce N95-quality mask-filter material

N95 is a US standard for particulate filtering; a material has to be able to block at least 95% of airborne particles. That material is comparatively expensive, but Mahesh Bandi — a physicist at the OIST Graduate University — has figured out how to make N95-quality stuff out of recycled plastic melted into a goo and spun out using a cotton-candy machine.

His paper on the process is here, and Interesting Engineering has a short write-up of how the technique works:

The new technique calls for the heating of ordinary plastics (like bottles or shopping bags), and then placing them inside cotton candy machines — also called candy floss machines. Then the machine spins the plastic into a material not unlike the mesh of cotton candy, which is electrocharged during the spinning process.

Afterwards, Bandi cuts the resulting material into small square snippets, and then enhances their electrostatic charge via putting them in proximity to the vent of a common air ionizer.

The new cotton candy-like filters were tested inside surgical masks, where they proved highly effective — but the masks weren't a realistic option. This is when Bandi designed his own mask to allow for a simple insertion and removal of filters — since each mask requires three — and made use of a 3D printer to create the final product.

Intense testing — which involved microscopic inspections and comparisons with N95 filters — saw the filters prove as effective at stopping the inhalation of coronaviruses as normal N95-like respirators.

The usual caveats about exploratory, early-stage experiments apply here — this is just preliminary work, no idea if it could actually scale or how reliable it'd be, etc.

But it's an extremely cool concept, great lateral thinking, and I love the idea of janky cotton-candy machines being dragged out of storage and used to help fight COVID-19.

(That CC-2.0-licensed photo of a cotton candy machine courtesy the Flickr stream of Tabrez Syed)